Abstract
Purpose: :
Hepatocyte growth factor (HGF) is a pleiotrophic factor with mitogenic, motogenic, and morphogenic activities. Recent evidence has suggested that HGF is a member of the neurotrophic factor family and plays an important role in the development, maintenance and neuroprotection of neurons and photoreceptor cells (prc). Due to its potential role in modulating adult retinal stem cells (RSC) we wanted to determine the expression status of the HGF–receptor (c–Met) on cultured RSC.
Methods: :
RSC were harvested from the outer retinal margin and cultivated as neurospheres in RCS medium supplemented with 20ng/ml basic fibroblast growth factor (bFGF) and epidermal growth factor (EGF) for two weeks. 10% fetal calf serum (FCS) was added and RSC were cultured as monolayers. Different neural stem cell markers (nestin, Oct4, Chx10 and Pax6) were used to determine their stem cell origin. Western blot and immunocytochemistry were performed using rabbit polyclonal antibodies detecting the ß–subunit of the c–Met receptor and its phosphorylated form.
Results: :
Isolated RSC were positive for all tested markers and negative for GFAP and rhodopsin confirming their neural stem cell nature and undifferentiated state. Expression of c–Met and its active form was consistently demonstrated by immunoblotting and immunofluorescence.
Conclusions: :
In cell replacement approaches the capability of subretinally injected RSC to invade an uninjured neural retina is limited. This might be due to physical barriers such as the outer limiting membrane and/or the lack of appropriate stimulating neurotrophic factors. Since RSC express c–Met receptor a pretreatment with HGF may significantly alter their invading properties and promote their survival.
Keywords: growth factors/growth factor receptors • retinal culture • retinal degenerations: cell biology